1. Field of the Invention
This invention relates to a soot treating apparatus for a dust collector, which is capable of collecting soot from exhaust gasses of engines equipped for the performance tests, before the exhaust gasses are discharged to the atmosphere. More particularly, this invention relates to an apparatus for burning soot collected by the dust collector.
2. Description of the Related Art
The present inventors filed the patent application which is directed to this kind of the soot treating apparatus (Unexamined Published Japanese Patent Application No. 6(1994)-317137). As shown in FIG. 2, this apparatus comprises a filter 2 disposed in an exhaust gas duct 1 through which the exhaust gasses pass, and a hopper 3 disposed on a lower portion of the filter 2. A normally-open type damper 1a is disposed in the duct 1 on an inlet side of the filter 2, and a normally-open type damper 1b is disposed in the duct 1 on an outlet side of the filter 2. In the duct 1 on an exhaust gas-downstream side of the filter 2 is disposed a backwashing air conduit 4 for introducing a compressed air thereto, and a normally-closed type valve 4a is disposed in the air conduit 4. A combustion pipe 5 is connected to a lower end of the hopper 3, and a heater 6 is disposed around the combustion pipe 5. A combustion medium 7 is inserted into the combustion pipe 5 where the heater 6 is disposed. A chamber 8 is disposed on a lower end of the combustion pipe 5. And a filter 8a is disposed in the chamber 8. An air blowing pipe 9a is disposed on an upper portion of the combustion pipe 5, and an air blowing pipe 9c is connected to the air blowing pipe 9a through a valve 9b. A blower 9e is connected to the air blowing pipe 9c through a heat exchanger 9d which is disposed around the combustion pipe 5.
When the soot is burned by the above-mentioned apparatus, the combustion medium 7 in the combustion pipe 5 is heated up by the heater 6. The damper 1b is closed, and the blower 9e is operated. After that, the valve 4a is opened only in a short time, then the compressed air is blown against the filter 2 through the air conduit 4. The soot deposited in the filter 2 is dropped on to the hopper 3. The soot 10 deposited on to the hopper 3 is transferred to the combustion pipe 5 by the air blown from the air blowing pipe 9a. The soot 10 transferred to the combustion pipe 5 is collected by the combustion medium 7, where the soot is burned due to the heat of the heater 6 to be made into the ashes. The combustion medium 7 allows the ashes of the soot 10 and air to pass therethrough. Most of the ashes are collected in the chamber 8, whereby the air including the ashes and blown from the air blowing pipe 9a is purified by the filter 8a to thereby be discharged to the atmosphere.
In the conventional soot treating apparatus for the dust collector, most of the ashes of the soot passing through the combustion medium store in the chamber and the rest of the ashes is collected by the air filter. Accordingly, there has been a problem that the air filter is incapable of collecting the ashes effectively and completely. Also, in the above-mentioned apparatus, it has been troublesome to take out the ashes collected in the chamber therefrom.
It is, therefore, an object of the invention to provide a soot treating apparatus for a dust collector, which is capable of collecting the ashes of the soot effectively and completely burned by the combustion medium.
It is, another object of the invention to provide a soot treating apparatus for a dust collector, which is capable of discharging the combustion gasses directly to the atmosphere, and dumping the collected ashes easily.
The invention according to a first embodiment is, as shown in FIG. 1, directed to a soot treating apparatus for a dust collector, comprising a filter 12 disposed on a passage 11 through which exhaust gasses pass for collecting soot included in the exhaust gasses, a hopper 13 disposed on a lower portion of the filter 12, a backwashing means for introducing a compressed air into the filter through an exhaust gas-downstream side of the filter 12 to drop the soot deposited in the filter 12 on to the hopper 13, a combustion pipe 15 connected to a lower end of the hopper 13, an air supplying means for supplying a combustion air into the combustion pipe 15, a combustion medium 30 of heat-resistant porous ceramic inserted into the combustion pipe 15, which is capable of collecting the soot 10 arriving at the combustion pipe 15 and of letting the combustion air pass therethrough, a heater 16 disposed around the combustion pipe 15, being adapted to burn the soot collected by the combustion medium 30, a heat exchanger 17 disposed around the heater 16, and an air filter disposed on gas-downstream side of the combustion medium 30, which is capable of collecting the burned ashes coming from the combustion medium 30 and of letting the combustion gasses pass therethrough, wherein the air supplying means is comprised of an air supplying blower 18b, an air nozzle 18a for jetting an air toward the combustion medium 30 from a side of the hopper, and an air pipe passage 18c disposed so as to pass through the heat exchanger 17 for connecting the blower 18b and the air nozzle 18a to each other, characterised in that the combustion medium 30 is capable of collecting the burned ashes as well as the soot 10, and the air filter is comprised of a plate 31 of heat-resistant porous ceramic, which is detachably disposed on the gas-downstream end of the combustion medium 30 so as to cross with the combustion pipe 15, having pores of average diameter from 300 to 700 xcexcm.
When the soot is burned to be treated, the soot deposited in the filter 12 by introducing the compressed air thereto by the air conduit 14 is dropped on to the hopper 13. The soot is adhered to the combustion medium 30 due to the combustion air supplied to the combustion pipe 15, and burned due to the heat of the heater 16. Most of the ashes generated due to the combustion remain in the combustion medium 30. The plate 31 prevents the combustion medium 30 from dropping from the combustion pipe 15, and also collects the rest of the ashes reliably which come from the combustion medium 30 after combustion. A clean air passing through the combustion medium 30 and the plate 31, which does not include the soot or the ashes, is discharged to the atmosphere. When the ability in which the combustion medium 30 can collects the soot or the ashes is lowered, the combustion medium 30 is renewed. Also, when the ability in which the plate 31 can collects the ashes is lowered, the plate 31 is renewed.
The air pipe passage 18c is warmed up by the heat exchanger 17 by using the heat of the heater 16 effectively. The combustion air is warmed through the air pipe 18c to be jetted from the air nozzle 18a as the warm wind. Whereby, the combustion efficiency of the soot at the combustion medium 30 is improved.
The combustion medium 30 is comprised of heat-resistant porous ceramic having pores of average diameter from 20 to 700 xcexcm. As porous ceramic, there are exemplified alumina and cordierite, etc., which are greater in heat-resistance. It is preferable that porous ceramic is of a pellet-like one or a chip-like one or a chip-like one which is greater in specific surface area. Otherwise, porous ceramic may be of a honeycomb-like one. The former pellet-like or chip-like porous ceramic has preferably pores of average diameter from 50 to 150 xcexcm, more preferably 100 xcexcm. The latter honey-comb-like porous ceramic has preferably pores of average diameter from 400 to 600 xcexcm, more preferably 500 xcexcm.
As described above, according to the invention, the soot which is dropped from the filter can be burned effectively by the short combustion pipe, so that all the soot can be made into the ashes. As a result, the ashes are less in harm compared with the soot, then the volume thereof becomes {fraction (1/100 )} of the soot. Since most of the ashes are remained in the combustion medium and the rest of the ashes is collected by the plate, the combustion gasses can be directly discharged to the atmosphere. Also, the ashes can be dumped easily by renewing the combustion medium and the plate.